An automatic ice making machine for making large volume of ice blocks automatically in which an evaporation pipe is provided in an ice making section led out from a refrigeration system having a compressor, a condenser and the like, is configured so as to form an ice block by supplying ice making water to the ice making section cooled by a coolant supplied circulatingly through the evaporation pipe, thereby dropping and releasing the obtained ice block by separation. The automatic ice making machine, which has an ice making water tank for retaining a required amount of ice making water, is configured so that ice making water in the tank is fed by pressure by a circulating pump to be supplied to the ice making section during the ice making operation, and that ice making water which has not frozen yet is collected in the tank and then fed to the ice making section again. When a detection device detects that the water level in the ice making water tank has reached a preset lower water level as the ice making operation continues, it is determined that the ice making in the ice making section has finished, thereby shifting the ice making operation to the deicing operation. While hot gas discharged from the compressor is supplied to the evaporation pipe by switching a valve of the refrigeration system, water from an external water supply is sprinkled over the ice making section as deicing water, so as to accelerate the melting of the frozen surface with the ice block (for example, see Japanese Examined Utility Model Publication No. Hei 3-17187).
As described above, in the automatic ice making machine which uses both hot gas and deicing water during the deicing operation, the deicing operation becomes longer and the ice making capacity per unit time has limitations. Also, use of deicing water results in increase in water consumption, thereby requiring a higher running cost.
Consequently, by utilizing the technology disclosed in the specification of U.S. patent application Ser. No. 2003-0155467, there have been attempts to shorten the amount of time required for the deicing operation. Specifically, the ice making section is composed of a metal plate and a heater so that an ice block is formed on the heater during the ice making operation and heat is generated in the heater by applying current during the deicing operation, in order to melt the frozen surface between the heater and the ice block thereby removing the ice block from the ice making section for deicing. According to this configuration, the deicing operation becomes shorter and deicing water becomes unnecessary.